Hi
I have a MOKI 210 in a 29% Bucker Jungmeister that is kind of heavy at 22 pounds but I am very happy with it.Have about 20 flights or so on it. Have used either SIG FAI fuel as well as Cool Power FAI with 4 oz of Castor added per gallon.

The last few days did some experimenting with different props and based on flight performance an APC 20 x 10W looks to have the best pull and climb for aerobatics.Will fly nicely at half throttle.

Prop types:
ZINGER 22 x 8 turns around 6,200 RPM and plan will fly level at about 2/3 throttle.
ZINGER 20 x 10 turns around 6,500 RPM but flys about the same. Maybe a little faster.
APC 20 x 10Wturns around 6,700 rpm and flys level a half throttle with excellent climb out at full throttle.
Loops are much larger with the APC prop.

This kind of mimics my experience with a OS MAX 1.6 2 cycle in a 1/4 scale WW1 Albatros Dva. With various 18 x 6 wood props the climb out was OK but sometimes marginal. With an APC 18 x 6W there was a much better climb out after takeoff and would fly well at half throttle.

The APC props may not look as nice from a scale model perspective and they are heavier but the performance increase was noticeable.

The MOKI 210 is the first MOKI for me and as long as I prime it well it starts very nicely. Runs like a top and lots of power.

I have a moki 135 in my CAP 10b, and without a doubt is a far more powerful, lighter engine than any of the chinese 26cc motors kicking around.

It turned the cap from a slug into a hilarious snap-rolling fool.

The only problem is keeping it running! I have a smoke system installed but if I have smoke on at about half throttle it seems to put the plug out. Has anyone else had problems with smokies on their mokies?

I love my 210's. There easy to start, easy to tune, and extremely reliable. I run mine on Omega FAI with added (3 oz per gallon) castor.

The Pitts M12 was scratch built from my own plans about 7 years ago. It weighs in at about 15 lbs and flies like a dream.

The Stinger is a blast with the 210. Hovers at 1/3 throttle.

Curt - that is a Stinger 120, right? I have one started, but it's off to the side right now and I have not yet bought an engine for it. I figured if I could find a Moki 2.10 that would be a killer choice. Do you now what your all up weight is? As I understand it the fuselage/tail seciton builds up fairly heavy.

I have a moki 135 in my CAP 10b, and without a doubt is a far more powerful, lighter engine than any of the chinese 26cc motors kicking around.

It turned the cap from a slug into a hilarious snap-rolling fool.

The only problem is keeping it running! I have a smoke system installed but if I have smoke on at about half throttle it seems to put the plug out. Has anyone else had problems with smokies on their mokies?

Rendegade, what is your favorite fuel mix you use in your Moki 1.35? Also what Glow plugs would you recomend. Thanks Capt,n

I alwayts used the Morgan FAI 0% nitro. Used to be under $10 a gallon. Man did my Moki 1.80 and 2.10 love the stuff. Really sipped it. Tons of power. I had the best luck with K&B 1L plugs. Less than $3 a pop.

I had a 1.35 and was flawless. I started it everytime by bouncing it off compression backwards. If it didn't start in 3-4 tries, something was wrong. I also have the 3.6 twin for a Spitfire one day....

Nice to see a thread on my favorite engines. I've been running Mokis for several years now (a couple of 2.10s a 1.80 and a 1.35). They are great engines and I love them. The 2.10 makes about as much power as a good 45cc gasser, so I use them to power all manner of large aerobatic aircraft. I currently have a 2.10 in a Great Planes Ultimate.

Once set up properly, a Moki will literally run for years without needing adjustment, but they do have a couple of quirks it's good to be aware of.

The 2 o-rings that seal the low-speed disk and keep it from rotating can shrink and harden with time. This can be hard to diagnose because it can't be "seen" when you tear down the carb. What happens as the o-rings loosen is that the low-speed disk then rotates due to engine vibration. On one of my engines, it rotated enough to completely block-off the fuel supply causing a deadstick situation.

The solution is to place a small dollop of silicon glue (I use the GOOP brand) where the low-speed disk meets the carb near the main needle valve flange. This solves the problem and keeps the disk from rotating. The silicon glue can easily be pried away for maintenance, tear down, etc. I only do this after break-in and once the low speed setting has been fine tuned. Obviously, the area where the silicon glue is to be applied has to be scrupulously cleaned and degreased prior to application.

By the way, I don't think I have ever had to adjust the low speed mixture once it had been set.

Another "quirk" is what I call the Large Fuel Tubbing Myth. Many users think these engines require all manner of special plumbing to ensure adequate fuel supply. I believe the originator of this thread mentioned something... Anyway, I don't mean to start a war, but this is false, what the engine requires is ADEQUATE FUEL PRESSURE. This must be supplied either by a pump or by a properly set up muffler. The commonly used BCM muffler (an otherwise fine product), sadly does not provide enough pressure to the tank, and thus the engine runs lean, overheats and quits.

Folks then start doing all sorts of silly things like using extra large tubing, drilling out their clunks (really) and so on. All you have to do is block-off one of the exit pipes on the BCM muffler and voila, great tank pressurization and fuel supply. BTW all my Mokis run on standard medium 3/32 fuel tubing. Though I haven't used them myself, Cline regulators are reputed to work well, if you want to place the tank in the middle of the aircraft.

I've had great luck with the OS "F" plug on all my Mokis and the following props for general sport flying:

ORIGINAL: LuvBipes
Another ''quirk'' is what I call the Large Fuel Tubbing Myth. Many users think these engines require all manner of special plumbing to ensure adequate fuel supply. I believe the originator of this thread mentioned something... Anyway, I don't mean to start a war, but this is false, what the engine requires is ADEQUATE FUEL PRESSURE. This must be supplied either by a pump or by a properly set up muffler. The commonly used BCM muffler (an otherwise fine product), sadly does not provide enough pressure to the tank, and thus the engine runs lean, overheats and quits.

Folks then start doing all sorts of silly things like using extra large tubing, drilling out their clunks (really) and so on. All you have to do is block-off one of the exit pipes on the BCM muffler and voila, great tank pressurization and fuel supply. BTW all my Mokis run on standard medium 3/32 fuel tubing. Though I haven't used them myself, Cline regulators are reputed to work well, if you want to place the tank in the middle of the aircraft.

It's interesting what you say about the fuel tubing. My Moki 1.35 was supplied with instructions that specifically point out that 3/32 fuel lines should not be used. I used the recommended 1/8th" size bore tubing, with feed, fill and pressure lines with 2 clunks. The engine was supplied by Just Engines.

Funnily enough, I use a BCM pitts muffler and I run it with both the exit pipes OPEN. Because I run my tank close to the bulk head and at the right height, I honestly don't need a regulator OR to alter the BCM. I firmly believe, however, that if I were to try and run this engine with 3/32" tubing, both exit pipes open AND with the tank too far away/wrong height, with no regulator to help aid with fuel metering - I reckon I'd run into problems.

It's not silly running with the fuel tubing recommended by the supplier, on the contrary - it's one less thing to worry about. If you look at the fuel nipple on the Moki 1.35 carb, it's much larger than the ones you find designed for 3/32" lines. My setup works very well for me.

So I guess based on what you're saying - we have a choice of running the Moki with standard size 3/32" fuel lines and modify your muffler by restricting the outlets along with installing a regulator OR running with 1/8th" fuel lines and leaving the muffler as is, thus eliminating the need for a regulator and giving the engine a chance to develop all the ponies it was designed to!

Horatio, no offense taken, everybody is entitled to their opinion, and I'm glad your methods work for you. However, recall that Just Engines is only a distributor of Moki engines for Great Britain not the manufacturer. They are not, therefore, the last word on how best to operate them. There are opposite views expoused by sources just as credible and I quote the instructions included with one of my Moki 2.10s (much larger fuel consumption than the 1.35), by Gerard Enterprises the U.S. distributor at the time:

===> "Be sure to use a fuel line that is large enough to allow an adequate fuel supply. (3/32" I.D. fuel line is the recommended size). If the engine won't run rich with 3/32" line, there is a restriction somewhere else in the fuel system" <===

Jim Gerard was the U.S. importer for many years and had great experience with these engines. I once spoke with him on the phone and he was also a very helpful person.

To see what I mean about BCM mufflers often not providing sufficient tank pressure, just compare the size of their exit openings to the stock mufflers. I have an OS 1.60, which uses the same basic BCM muffler as the Moki 1.80 (except for the mounting flange) and the combined 2 openings have at least twice the exit area as the stock OS muffler supplied with the engine. It's no wonder the engine runs better with one exit shut off.

Oh, the bipe in my avatar is a kit built Goldberg Bucker that's currently powered by a OS 120 AX (lovely engine, btw).

Hi,
I have come to this website because of the problems with my Moki 1.8. I bought one used several years ago and finally got around to building a plane for it. I put it in a 35cc Aeroworks Extra with a Pitts muffler. I got it to run OK (5% Cool Power) initially in the plane but then it started running poorly and dying shortly after take off. I had some suspicions about the needle valve since it had been rotated to a different position ( I assume the original owner didn't like the position of the fuel nipple).

Anyway, I just couldn't get it to run consistently so I bought a new carb/needle valve assembly from Just Engines. That seemed to make no difference or perhaps was worse. I would prime it up and it would run out the prime and stop.
I finally put it on a test stand and experimented with fuel, carb setting et. I switched to an OS F plug, FAI fuel, and finally found that with the low speed dial about 1/16" on the + side it would run.
Put it back in the plane and got one good run in the garage and then it wouldn't start again no matter how much prime I added.
From what I have read on this listing it appears that it isn't getting enough fuel. I am using the tank set-up that Aeroworks provided with an over-sized brass fittings so I'm sure everything has a good seal. Should I be blocking off one the pipes on the Pitts?
I have ordered a CLine regulator. Is this necessary?
Thanks,
Bill

Well, it's interesting that 2 suppliers give such conflicting advice, but just as you say - whilst they are credible, they will only offer their advice or written instruction based on what has worked for them. Sadly, the gent Paul who sold me the engine from Just Engines passed away shortly after I received mine, making further queries rather difficult. What does surprise me is how little is offered from Moki in the way of written instructions.

Looking around on the internet at people using the BCM pitts muffler, many of them have the exact same issue with the exits. I personally have not experienced this issue, but it obviously exists.

@ Pura

Seemingly there are 3 potential issues that can work (or should that be not work?) in combination with each other, all of which result in fuel starvation.

The Moki rotary low speed adjuster can move with the rotary barrel - either due to the O-ring or in my case it was lightly gummed with castor. It then completely shuts off fuel supply.

The O-ring on the carb intake doesn't seal sufficiently (between the carb and engine's casing). A second O-ring solves the problem.

3/32", 1/8th" and 5/32" bore tubing determines fuel flow. It stands to reason that if you're not getting enough fuel into the carb, larger diameter bore should help. Likewise, reducing the exit pipe's area as discussed will increase the back pressure to the tank. I use 1/8th" tubing, which is the middle of the 3 size options. Also, it seems to fit the nipple better IMHO.

Tank position is critical also. If it's too low or too far away, a regulator is supposed to make a real difference once properly setup.

Hi,
I have since tried clamping off one exhaust ( I put rubber exhaust extensions on the outlet pipes) and it seemed to help a bit. I got a couple of runs, but noticed that after running a while - say 1 or 2 minutes- and I throttled down to check the low and high rpms the engine would begin to falter and then die. If I ran it consistently at high speed that didn't seem to happen so much, although it did happen, and I think that it was overheating, which would suggest that it is running lean no matter how much I open the needle valve.
When I installed the new carb I put Ultra Copper high temp silicone at the base so I think that it has a good seal. It looks like everything is pointing to not enough fuel. The fuel tank is also a fair distance back from the firewall and I have a feeling that even with larger diameter fuel tubing that it just can't draw enough fuel fast enough. Funny that I did get a couple of good flights, but maybe I was just lucky.

As a final question- are these set-up problems typical of all bigger glow engines? I was wondering if the OS 160 or other big engines in that range have the same problem with drawing enough fuel.
Thanks,
Bill

I'm a firm believer of belt and braces. I think a pump will most likely cure it, providing there is nothing nasty lurking in your carb or lines or air leaks. At the same time, using 1/8th" lines will also help. Keep us posted.

Just out of interest, have you seen the before and after running videos on page 1? Does your engine sound/behave like the 'before' video?

Hi,
I have since tried clamping off one exhaust ( I put rubber exhaust extensions on the outlet pipes) and it seemed to help a bit. I got a couple of runs, but noticed that after running a while - say 1 or 2 minutes- and I throttled down to check the low and high rpms the engine would begin to falter and then die. If I ran it consistently at high speed that didn't seem to happen so much, although it did happen, and I think that it was overheating, which would suggest that it is running lean no matter how much I open the needle valve.
When I installed the new carb I put Ultra Copper high temp silicone at the base so I think that it has a good seal. It looks like everything is pointing to not enough fuel. The fuel tank is also a fair distance back from the firewall and I have a feeling that even with larger diameter fuel tubing that it just can't draw enough fuel fast enough. Funny that I did get a couple of good flights, but maybe I was just lucky.

As a final question- are these set-up problems typical of all bigger glow engines? I was wondering if the OS 160 or other big engines in that range have the same problem with drawing enough fuel.
Thanks,
Bill

Pura, a question: can you get your engine to 4-cycle? By that I mean, can you get it to run sloppy rich by opening the main needle valve? If not, you have a fuel supply problem and you'll have to keep looking for the cause. Have you tried running the engine with the cowl off? Worth a try so as to eliminate overheating as a cause of your problems.

More generally, no - large 2-stroke glow engines are very easy to start and run. I also have the OS 1.60 and it's a big *****cat, loves a APC 18X8 prop and is quite lightweight for the power it produces. Incidentally, once set up correctly Mokis are extremely reliable requiring virtually no maintenance (other than occasional after-run oil) for years of service.

How do you find the Moki compares to the OS 1.60 in terms of power output cc for cc? OS engines are always used as a bench mark. Moki engines seem to have a very high compression ratio, thus they run extremely well on straight fuel, but it's fair to say that they are 'stiffer' to flick start by hand as a consequence.

@ Pura

I've noticed that after I prime my engine, if I don't get straight onto starting it, the fuel in the line will just slowly move back down the line towards the tank. This hardly matters if you use an electric starter, but can be quite a challenge if you like the traditional flick start.

The Moki engines really are a no compromise performance engine. But listen to the low idle on them - it's amazing. Once warm, you can virtually get them to 'pop..pop..pop' speed before they allow you to cut them.

I haven't had to change the needle settings at all since getting it to the sweet spot. The low speed dial is very sensitive to changes, so you have to be patient.

Hi,
Thanks for all the comments/ suggestions. LuvBipes, Thank you for the point on the cycle. I realized in working with the engine on the test stand, that I could never really get it to 4 cycle, I would open and close the needle valve but it really didn't make any difference to the the 2cycle/ 4 cycle. Of course it would run rich, but never 4 cycle.
So in looking at the set-up on the test stand vs. the aircraft, the big difference was the distance of the tank to the engine. In the Aeroworks as with other designs the tank is some distance away and I also had a fuel filler/diverter on the fuel line. Bypassing the filler and setting the low speed wheel to the plus side made it possible to get some runs on the plane, but it is clear that the engine tends to run on the lean side and that after running it for a few minutes it would often die when I tried to vary the throttle. ( Just as you depicted in the videos, Horatio)
I think now that it was over heating. The cowl was off by BTW.
So it seems that lack of sufficient fuel is the source of trouble. I have ordered a Cline regulator but was reading elsewhere that some people suggested using a "header tank". How is that set up and would it make a difference?
Bill

A header tank is a smaller second tank that helps even-out fuel supply. Because the header is smaller, it can be plumbed in to a more suitable, higher position. The header tank should have it's own clunk, and when refuelling, the filler should go to the header. When the header fills completely, the main tank begins to fill. It would probably help, assuming that: 1) it's plumbed in correctly and 2) you can get the header into the optimum position.

You've indicated the problem is a tank that is too far away and too low. A perry pump would probably help, in some cases you need to use the perry in conjunction with a header. As you mention the Cline regulator is on order, you may as well check out all the Cline info here on RCU - there's loads of stuff on it. Lots of people swear by them and they don't have to be adjusted like the perry. Either way, you need to use crankcase pressure on a 2 stroke engine to enable the Cline to function. That means you'll have to drill/tap a nipple into your Moki. ~Gulp!~

Check your existing tank is able to pressurize - actually blow down a piece of tubing into the tank, with the other tube/s closed off. If it leaks air under pressure, that's a problem.

Pura, a header tank is not necessary if adequate fuel pressure is present either from the muffler or a pump setup such as the Cline. As mentioned above, do a search in this forum as there is a ton of good info on how to set them up. I have long ago stopped using remote fuel fillers due to them restricting fuel flow and occasionally springing a leak. The 3 line system using a fuel dot is both neater and cheaper. The line to the dot should go to the bottom of the tank or a to a 2nd clunk.

It's not difficult to tap the crankcase for the pressure fitting required by the Cline. However, if you have no experience drilling & tapping into aluminum, then your nice Moki is NOT where you should practice. In that case, find someone in your club who knows how to do it. BTW, I've found that a small dab of JB Weld (or similar high temp epoxy) make the installation permanent and leak proof.

I use a 3 line system with ASP fuel dots. I find the the filler line has worked fine with a second clunk. When I referred to filler, I really mean the 3rd line.

The perry pump, under some circumstances, simply doesn't work properly UNLESS you use a header tank. I haven't heard of anyone needing to use a header with the Cline regulator. As I understand it, the Cline only allows fuel to flow as the carb demands it. There's no pressure between the Cline and the carb. There's also no risk any remaining fuel draining from the tank of the aircraft while you drive home from the field. On the other hand, the Cline is usually used with four stroke engines, where as the Perry VP 30 (pump and regulator) is often commended for 2 stroke use.

You'll need to find out what size drill bit you need and what size tap, depending on the size of nipple you use - I imagine the only safe way to do this is remove the backplate from the Moki, and either drill it very carefully with a dremel, or better still, get it done using a pillar drill.

I have Moki 135-180-210 engines all on scratch built warbirds . The 135 is on an 84" ws 14lb FW190 running a 16 oz tank.The only issue I have had with it is after several minutes of running it would hesitate on takeoff.I forgot to say I am using Bisson muffler. I rolled the exhaust outlets smaller on the tips and corrected the problem. I seldom fly WOT and usually fly8-10 minutes.
The 180 is on a FW190 80" ws 18lb running a 16 x10 3 blade bisson muffler with a 20 oz tank muffler pressure. No issues at all with this setup.
The 210 is on a ME109 84" ws 18-10 20-8 prop bisson muffler 24oz tank mounted back toward CG.I use a Cline regulator on it with great results. My only concern with the Cline regulator is the pressure on the tank. After a flight I bleed the pressure off and you can actually HEAR the fuel tank in the plane contract. It will squirt fuel 3 feet. The system runs great just like the others.
I run OMEGA FAI when available but 5% otherwise. I have 4 other 120-180 MOKIS and all are extremely reliable when dialed in.
I would call my planes fun scale scratch built that really don't get [or deserve ] much attention at local fly ins but the one flip start usually draws a comment.
I have os,enya, magnum and thunder tiger engines too but the Mokis are my favorite.